Nonlocal Mechano-Optical Metasurfaces.

Tunable metasurfaces enable active and on-demand control over optical wavefronts through the reconfigurable scattering of resonant nanostructures. Here, we combine novel insights inspired by mechanical metamaterials with the unique sensitivity of nonlocal optical resonances to interparticle distances to achieve giant tunability in mechano-optical metasurfaces where the mechanical metamaterial and optical metasurfaces are integrated in a single nanopatterned material. In a first design, judiciously engineered cuts in a flexible substrate enable large, strain-induced extension of the interparticle spacing, tuning a high-quality-factor resonance in a silicon nanoparticle array across a very broad spectral range. In a second design, we eliminate the substrate and demonstrate a nanopatterned silicon membrane that simultaneously functions as a mechanical metamaterial and an optical metasurface with large tunability. Our results highlight a promising route toward active metasurfaces, with potential applications in tunable filters, reconfigurable lenses, and dynamic wavefront shaping.